Gear Quality Research Articles

Research on High-Precision Measurement Method for Small-Size Gears with Small-Modulus.

Small-modulus gears, which are essential for motion transmission in precision instruments, present a measurement challenge due to their minuscule gear gaps. A high-precision measurement method under the influence of positioning errors is proposed, enabling precise evaluation of the machining quality of small-modulus gears. Firstly, a compound measurement platform for small-modulus gears is developed. Using a 3D model of the measurement system, the mathematical relationships governing motion transmission between various components are analyzed. Secondly, the formation mechanism of gear positioning error is revealed and its important influence on measurement accuracy is discussed. An optimization method for spatial coordinate transformation matrices under positioning errors of gears is proposed. Thirdly, the study focuses on small-sized gears with a modulus of 0.1 mm and a six-level accuracy. Based on the aforementioned measurement system, the tooth profile measurement points are collected in the actual workpiece coordinate system. Then, gear error parameters are extracted based on the established models for tooth profile deviation and pitch deviation. Finally, the accuracy and effectiveness of the proposed measurement method are verified by comparing the measurement results of the P26 gear measuring center.

Experimental Investigation on Surface Characteristics of Finish Hobbed Gear using Grey Relational Analysis

Introduction: Spur gears are important for transferring motion and power among shafts. The surface characteristics of these gears are important for their life and smooth operation. To improve profitability and customer satisfaction, a study was conducted to analyze the surface quality of spur gears produced through CNC hobbing machining. Objectives: The objective this investigation is to conduct experimental trials to estimate the best hobbing parameters to minimize surface roughness and microgeometric deviations. In this investigation, effect of varying cutting speed and feed rate on surface finish have been reported. Methods: An experiment are conducted according to Taguchi L9 experimental design. Grey Relational Analysis is performed to estimate the optimum machining parameters. Results: The experimental finding reveals, at cutting speed 400 rpm, the feed rate 8 mm/min, and depth of cut 3.91 mm gives good quality of surface (Ra 0.5530). The gear hobbing process has increased to a greater level of performance. The roughness of the flank surface and microgeometry deviations decreases with an increase in hob cutter speed. Conclusions: This ultimately reduces the inherent vibrations between the hob cutter and the gear blank, thus minimizing microgeometric deviations. The variation in feed rate was noticed and had a very significant impact on the efficiency and surface quality of the gear. The study recommends that a cutting speed of 400 rpm is the most effective for obtaining the best results.

A Grinding Method with an Innovative, Efficient, and Weight-Saving Design for Double Helical Gears

Grinding technology exerts an enormous effect on the surface quality of double helical gears, which are subject to stringent requirements in the aviation industry. This study presents a novel gear-gap-space-borrowing grinding method that diverges from existing techniques. Unlike conventional approaches, this method mitigates the design–manufacturing conflict by exploiting the opposing gear gap space. By borrowing space, the grinding wheel’s size can be enlarged to enhance machinability, diminish the width of the undercut, and align with the lightweight design imperative of double helical gears. The relationship between the grinding wheel diameter and the design parameters of double helical gears is analytically established, leading to the formulation of design rules. These rules facilitate the rapid selection of appropriate grinding wheel sizes for the space-borrowing method. Additionally, through geometric modeling and experimental validation, the optimal gear undercut width and the maximum wheel diameter are determined. The validity and accuracy of the proposed method are verified by simulations and experimental investigations. The study quantitatively evaluates the benefits of this method, including the expansion of the grinding wheel size, the reduction in double helical gear weight, and enhancements in processing efficiency and quality, providing a comprehensive comparison and discussion of these improvements.

Эластичные хоны для полирования профилей зубьев термообработанных цилиндрических колес специального назначения

Introduction. The most important component of the technological process of manufacturing of gear wheels of critical products is the operation of teeth honing. Special requirements are imposed on the surface quality of special-purpose gears, where imported abrasive tools were used, the supply of which in modern economic conditions is impossible. Purpose of work: development of formulation, technological equipment and technology of manufacturing of elastic diamond gear hones instead of imported ones for teeth honing of gear wheels of special purpose. Research methods. Subject of research are samples of imported elastic gear hones and created domestic analogs. The mechanical properties, morphology and chemical composition of the abrasive (diamond) layer of the working surface of the teeth and the annular gear were determined. The content of chemical elements was controlled in separate points of the surface and by scanning over the area on a scanning electron microscope. The formulation and technology of production of annular gears were determined. Results and Discussion. Designs of molds for forming the abrasive layer and the hub of the gear hone are developed. The peculiarities of morphology of the material of the working layer and the annular gear of the elastic diamond gear hone are revealed. On the basis of the conducted research, domestic analogs of materials of constituent elements of the gear hone are determined. Two manufacturing technologies were considered: pressing and injection molding. Two molds were made to test the technology: a simplified model consisting of two teeth and a round mold. Several methods of manufacturing hone teeth were analyzed: manufacturing of an abrasive layer with different degree of pre-vulcanization, subsequent introduction of gear material and final vulcanization of the whole product. The mechanical properties of the materials of the working abrasive layer and the annular gear were determined. The chemical composition of the components of the hone and the boundary zone are studied. As a result of the conducted research, recommendations on the formulation of the abrasive layer and the annular gear, technology of manufacturing of the gear hone intended for final treatment of teeth of heat-treated spur wheels of special purpose are given.

Workpiece Quality Prediction for Gear Hobbing based on Sensor Data

In gear hobbing, as in other soft machining processes, it is essential to maintain the required workpiece quality to avoid rejects or increased rework. To track the workpiece quality, the manufactured gears usually have to be measured on a measuring machine. In order to ensure workpiece quality even with long measuring intervals, process monitoring offers an approach to check the gear quality already during the manufacturing process. In this report, the potential of acceleration data with regard to the assessment of workpiece quality is investigated. In this investigation, both analytical and artificial intelligence based methods are considered.

The effect of gear-manufacturing quality on the mechanical and thermal responses of a polymer-gear pair

Abstract Gear-manufacturing quality affects the load sharing between the meshing gears as well as the load distribution along the width of the tooth. This study aims to investigate the effect of gear-manufacturing quality on the mechanical and thermal states of polymer-gear pairs and consequently on their lifetime. The deviations of the geometric quality parameters, i.e., the lead profile and pitch, were found to have a substantial effect on the stress (root and flank) state of the gear. The effect of the lead deviation was found to be most pronounced for the quality grades Q12 to Q10, where depending on the load, a 30–80% stress reduction was observed when improving the gear quality from Q12 to Q10. Improving the quality from Q10 to Q8 did not lead to a substantial improvement in the load distribution and the observed stress reduction was in range of 5–20%. Similar trends were found for the pitch deviation, where again the most pronounced stress reduction was seen when improving the quality grade from Q12 to Q10. The study reveals where the most effective changes, leading to an increased gear-life, can be achieved. Improving the gear quality grade from Q12 to Q11 proved to have a much more substantial effect than improving the gear quality from Q9 to Q8. Considering that improving the gear quality from Q12 to Q11 or even Q10 can be achieved by a proper tool design and corrective iterations with the right process parameters, while improving the quality from Q9 to Q8 is by far more challenging. A novel methodology is proposed to assess the effect of the gear’s quality on the generation of heat and the resulting operational temperature. The proposed methodology enables more accurate prediction of the gear pair’s operating temperature.

A longline survey for spurdog distribution and life history along the Norwegian coast

AbstractTo improve spatiotemporal data collection and inform future spurdog Squalus acanthias stock assessment, a new dedicated longline survey was initiated in 2021 in coastal waters of southern Norway. The survey comprised a mixture of randomly predefined stations to facilitate unbiased abundance estimates and supplementary stations including informant putative hotspots. During 25 survey days in autumn 2021, 287 stations were sampled, of which 280 were categorized as “satisfactory” in terms of gear quality deployment. Spurdog catches (n = 954) were more abundant in southeast coastal shallower waters (19–150 m). No length, sex, or maturity stratified schooling behavior was found with increasing catches. Females were more abundant and larger than males, but males were older. Growth and reproduction parameters were within ranges reported for the stock. Our results provide valuable input for spurdog survey designs with regards to optimizing boat time, location of stations, and biological sampling protocols. The survey provides important data for monitoring the spurdog stock and other data‐limited species, especially considering the newly re‐opened spurdog fishery but also to study possible future effects of climatic changes on spurdog distribution.

Effect of Process Parameters on the Crystallinity and Geometric Quality of Injection Molded Polymer Gears and the Resulting Stress State during Gear Operation.

The quality of gear manufacturing significantly influences the way load is distributed in meshing gears. Despite this being well-known from practical experience, gear quality effects were never systematically characterized for polymer gears in a manner able to account for them in a standard calculation process. The present study employs a novel combination of numerical and experimental methods, leading to a successful determination of these effects. The findings of the study enhance existing gear design models and contribute to a more optimized polymer gear design. The study first explores the effect of injection-molding parameters on the gear quality and secondly the effect of resulting gear quality on the stress conditions in a polymer gear pair. For the gear sample production, different combinations of process parameters were investigated, and a classic injection-molding and the Variotherm process were utilized. Gear quality and crystallinity measurements were conducted for all produced gears, providing insights into the correlation between them. Based on the evaluated gear quality of produced samples, the effect of gear quality was further studied by numerical means within a meaningful range of quality grades and transmitted loads. Special attention was dedicated to lead and pitch deviations, which were found to exert a noteworthy influence on the stress state (both root and flank) of the gear. The effect of lead deviation was most pronounced when improving the gear quality from grade Q12 to grade Q10 (30% to 80% stress reduction, depending on the load). However, enhancing the quality grade from Q10 to Q8 yielded less improvement (5% to 20% stress reduction, depending on the load). A similar pattern was evident also for pitch deviations.

An ease-off tooth surface redesign for spiral bevel gears considering misalignment under actual working conditions

To improve the loaded performance of spiral bevel gears, a novel tooth surface redesign method considering misalignment is proposed based on ease-off. First, the digital features of the contact pattern were extracted, and the equivalent misalignment was obtained by an optimal method according to the minimum deviation of the contact path. Second, a pinion target surface whose performance under misalignment was consistent with the original gear in standard position was built, and a pinion surface with good meshing performance under misalignment was redesigned with equivalent misalignment. Third, the flank modification was carried out to cut down on the loaded transmission error of gear under misalignment. Through simulations, it is found the transmission error and the contact path of redesign gear considering misalignment were the same as original gear in standard position. The loaded transmission error amplitude of original gear under misalignment was 43.91% higher than original gear in standard position, and the loaded transmission error amplitude of redesign gear after optimization under misalignment was 44.73% lower than original gear in standard position and 61.60% lower than original gear under misalignment. The tooth surface stress of redesigned gear after optimization under misalignment was also significantly improved. This proposed redesign method, which considers misalignment on the basis of ease-off, can greatly improve the loaded meshing quality of gear under actual working conditions.

An analytical method for the meshing performance of deviation surface of spiral bevel gear based on a one-dimensional probe

The meshing performance is a significant indicator for evaluating the machining quality of spiral bevel gear. The flank contact accuracy (FCA) and flank geometric accuracy (FGA) are important aspects of meshing performance, and both are indispensable. In the actual production process, due to the lack of professional meshing performance analysis (MPA) software, the flank geometric structure cannot be reflected based on the FCA, and the actual meshing state cannot be reflected by the FGA, which cannot meet the manufacturing requirements of high-quality gear. Therefore, a MPA method for deviation surface of spiral bevel gear is proposed based on the gear measuring center using a one-dimensional probe. By constructing the deviation surface, the flank meshing model is established, and the meshing parameters are determined. Aiming at the complexity of solving the meshing model, a method for decreasing the dimension of the meshing equations is proposed by establishing the mathematical relationship between the rotation angle and the normal vector, which improves the solution accuracy of the meshing point. The intersection points of the adjacent transmission error curves are taken as the meshing in and out points, and then the actual position of the contact pattern is accurately determined. The instantaneous contact ellipse is obtained by using the method of a cylindrical surface intercepting the deviation surfaces, which not only simplifies the solution algorithm, but also obtains the contact pattern more in line with the actual situation. Finally, the transmission error and contact pattern are digitally characterized. The experimental results show that the digital and actual patterns have good consistency. Flank geometry and gear meshing are organically linked based on the proposed method, and the actual meshing state can be predicted according to the flank topology deviation, which provides important theoretical support for the improvement of the machining quality and meshing performance of the spiral bevel gear.

Selection of abrasive tools and cutting modes to improve the quality of gears and gear blocks

The paper analyzes the advantages and disadvantages of tools for tooth grinding and tooth honing, the areas of their application are noted. The issues of correction and restoration of grinding wheels and hones are considered in detail, recommendations are given when choosing coolant and oils. It is noted that the accuracy and quality of gears and gear blocks depend on the correct choice of tools for finishing operations. A comparative analysis of the effect of the processing method on the surface quality of the teeth is carried out.

Influence of single phase NiS nanoparticles as lubricant additive in microscale deformation of copper gear

ABSTRACT Demand for miniature gears is increasing daily due to huge development in MEMS and microdevices. As a result of this drive towards miniaturisation, microsystem technologies are becoming increasingly important. In this concern, researchers are interested in developing a micro forming process to manufacture highly accurate micro gears, improved operational and functional characteristics, capacity to perform in hazardous environmental conditions, and longer service life. Single-phase NiS nanospheres were developed using a high-temperature wet chemical method and were dispersed in engine oil (SAE 20 W-40) for further forming process. During plastic deformation (micro-scale), the combined grain size effects and NiS nanoparticle added lubricant on formability and interfacial friction of the micro gear are investigated. The grain size effect significantly impacts the micro gear’s formability during micro forming. The grain size and orientation significantly influence the microscale deformation process. Due to the size effect, the microhardness value at the centre and the tooth varies considerably. Due to the existence of NiS nano additive lubricant, the surface quality of micro gear improved significantly. The findings of this work help to comprehend the properties of nano additive lubricant and how it behaves tribologically throughout the micro-forming process.

Investigation of Spatial Symmetry Error Measurement, Evaluation and Compensation Model for Herringbone Gears

In the machining process for herringbone gears manufactured by numerical control gear-shaping machines, out-of-tolerance problems of symmetry error generally exist. This paper proposed a high-precision control of spatial symmetry error in the one-time forming machining for herringbone gear. To improve the machining symmetry accuracy and quality of herringbone gear, a mathematical model of measurement, evaluation and compensation for spatial symmetry error was established based on the least square method. Meanwhile, a new shaping machining method based on spatial symmetry error detection and compensation was proposed. The test results indicated that the proposed method can maintain symmetry within 0.02 mm. This study provided a novel spatial symmetry error detection and compensation machining method for herringbone gear that has advantages compared to traditional methods in terms of machining accuracy, efficiency, and continuous machining type.

Using multi-flexible body dynamic analysis and the Taguchi method to decrease the variation of output angular velocity in a double circular-arc harmonic gear drive

The performance of a double circular-arc tooth harmonic gear drive, which offers advantages over traditional designs, such as lower stress during contact and increased fatigue life, was investigated in this research. The gear drive’s meshing was simulated using dynamic analysis software RecurDyn, and a significant variation in output angular velocity was observed. To address this issue, experiments were planned using the Taguchi method with the L9(34) orthogonal table. The data was analyzed using techniques such as average value calculation, signal-to-noise ratio calculation, variance analysis, and response chart analysis to identify the control factors with the greatest impact on output angular velocity variation. It was found that an improved design with lower output angular velocity variation could be obtained by adjusting these control factors to optimal levels. The findings suggest that the transmission quality of double circular-arc harmonic gear drives can be enhanced by combining multi-flexible body dynamic analysis with the Taguchi method.

Optimising the Geometric Parameters of a Gear in a Tractor Transmission Under Constraints Using Kisssoft

Abstract We optimise the speed gears in a tractor transmission with KISSsoft software under three constraints: input power torque, transmission system volume and the gear ratio for each speed. This study aimed to optimise the module, face width, gear quality, centre distance, number of teeth, helix angle, addendum modification coefficient and pressure angle for each speed while considering the above constraints based on an optimisation chart. Tooth bending stress, tooth contact stress, contact ratio and specific sliding were considered during optimisation. Additionally, the effects of changes in a module on the gear profiles, overlap ratio, number of teeth and weight of the gear pair were examined. Strength calculations of gear pairs that were optimised and defined for all geometric parameters with KISSsoft were calculated with the mathematical model described in ISO 6336, and results were then compared. Finally, backlash was minimised for all gear pairs as defined with geometric parameters, and all dimensions and tolerances were determined for gear inspection after manufacturing. A concept design was also presented. We conclude that both the KISSsoft results and mathematical model results are within the range of the target value.

Study on gear meshing power loss calculation considering the coupling effect of friction and dynamic characteristics

Gear transmission system is widely used in many mechanical equipment to achieve power transmission and rotational speed changes. Meshing power loss is one key index to assess the performance of a gear system, which directly influences heat generation and lubrication, etc. Over the past decades, many computational models of gear meshing power loss have been proposed to support gear design and optimization. However, the coupling effect between the gear friction and dynamic characteristics are usually ignored, including time-varying meshing stiffness (TVMS) and dynamic meshing force (DMF), which are not conducive to accurate calculation and improvement of meshing power loss. Therefore, an improved gear meshing power loss calculation method is proposed to settle this problem in this paper. With the proposed method, the friction calculation model is established considering the effect of DMF and surface roughness based on mixed elastohydrodynamic lubrication (EHL). Then the TVMS is obtained with the friction force along the meshing line and DMF was taken into consideration. On the basis of modelling of friction and TVMS, a six degrees-of-freedom (DOF) gear dynamic model, as well as a power loss iteration calculation process are established and studied. The effects of gear surface manufacturing quality and loads on power loss are analyzed. Furthermore, a gear meshing power loss experimental setup is constructed to verify the effectiveness of the proposed method. The results show that this method is in better agreement with the experimental results than the traditional method which does not consider the coupling effects.

A Digital Twin-Based State Monitoring Method of Gear Test Bench

The gear test bench is important equipment for analyzing gear performance, detecting gear quality, and providing basic data for gear design and machining. In order to monitor the running state of the gear test bench, predict its running performance both timely and effectively, and guarantee its stable operation, a digital twin-based state monitoring method of the gear test bench is proposed in this paper. The state monitoring system of the gear test bench based on the digital twin model is constructed to simulate its normal running state in real time. On this basis, through the acquisition of physical information of the gear test bench, the developing of the state monitoring system, and the simulation of the digital twin model, the real-time state monitoring of the normal operation gear test bench is realized. The test results of the closed power flow gear test bench show that the digital twin simulation results of the gear test bench are basically consistent with it. The proposed state monitoring system can map the normal running state of the gear test bench, so as to realize the running state monitoring of the gear test bench.

Determination of the Accuracy of the Straight Bevel Gear Profiles by a Novel Optical Coaxial Multi-Ring Measurement Method.

Straight bevel gears are widely used in mining equipment, ships, heavy industrial equipment, and other fields due to their high capacity and robust transmission. Accurate measurements are essential in order to determine the quality of bevel gears. We propose a method for measuring the accuracy of the top surface profile of the straight bevel gear teeth based on binocular visual technology, computer graphics, error theory, and statistical calculations. In our method, multiple measurement circles are established at equal intervals from the small end of the top surface of the gear tooth to the large end, and the coordinates of the intersection points of these circles with the tooth top edge lines of the gear teeth are extracted. The coordinates of these intersections are fitted to the top surface of the tooth based on NURBS surface theory. The surface profile error between the fitted top surface of the tooth and the designed surface is measured and determined based on the product use requirements, and if this is less than a given threshold, the product is acceptable. With a module of 5 and an eight-level precision, such as the straight bevel gear, the minimum surface profile error measured was -0.0026 mm. These results demonstrate that our method can be used to measure surface profile errors in the straight bevel gears, which will broaden the field of in-depth measurements for the straight bevel gears.

Gear Shift Quality Enhancement Parameters in Light Commercial Vehicles

In the present scenario enhancements of human ergonomics in Light commercial vehicles are imperative to implement customer comfort in vehicle level. Thus the gear shift mechanism plays an important role in the interface between the driver and vehicle. An exact and smooth running gear shift feel typically depends on the combination of both internal and external shifting elements of the gearbox and Change shift operation(CSO) system. The objective of this paper is to explain the parameters that impacts the gear shift quality and how it is improved by taking multiple design iterations in Light commercial vehicle platform through both objective and subjective evaluations. These iterations are given better results on gear shift feel in dynamic as well as static condition. This lead us to facilitate better shift comfort to end users. The content of the paper is limited to the scope of gear shift quality improvements at manual transmission and change shift operation components.

Sound intensity analysis of straight bevel gears finished by using AFF process

This article reports using the Abrasive flow finishing (AFF) process to finish straight bevel gears (SBG) to improve their microgeometry errors and surface characteristics. Microgeometry errors, surface roughness parameters, and dual flank roll testing parameters was compared for unfinished and the AFF finished SBG. An indigenously developed bevel gear test rig was used for the sound intensity measurement and experiments were conducted by varying speeds at four levels. Finishing of SBG by the AFF process reduced their microgeometry errors, surface roughness, and improved functional performance parameters, resulting in reduced sound power generation. This study proves the potential of the AFF process to improve gear quality and help to establish it as a cost-effective, productive, and sustainable non-traditional solution for high-quality gear finishing.